
\documentclass[a4paper]{article}
\usepackage{pgfplots}
\usepackage{pgfplots.assert}

\begin{document}

\tracingcommands=2\tracingmacros=2

\makeatletter
\pgfplotssetcoordmathfor{x}{float}
\pgfplotssetcoordmathfor{y}{float}
\pgfplotssetcoordmathfor{z}{float}
\pgfplots@xislineartrue
\pgfplots@yislineartrue
\pgfplots@zislineartrue

\def\pgfplotsqpointxy#1#2{%
	\xdef\X{#1}%
	\xdef\Y{#2}%
	\xdef\Z{}%
}%
\def\pgfplotsqpointxyz#1#2#3{%
	\xdef\X{#1}%
	\xdef\Y{#2}%
	\xdef\Z{#3}%
}%

\def\CS#1 cs={%
	\pgfutil@ifundefined{tikz@parse@cs@#1}{%
		\pgfplots@error{no such cs:#1}%
		\def\next{}
	}{%
		\def\next{\csname tikz@parse@cs@#1\endcsname}%
	}%
	\next
}

\CS axis cs=(0,1)
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{1Y1.0e0]}{\Y}{}
\pgfplotsassertequalstok{}{\Z}{}


\CS axis cs=(0,{min(0,-1)})
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{2Y1.0e0]}{\Y}{}
\pgfplotsassertequalstok{}{\Z}{}

\CS axis cs=(0,1,-1)
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{1Y1.0e0]}{\Y}{}
\pgfplotsassertequalstok{2Y1.0e0]}{\Z}{}

\CS axis cs=(0,{min(0,-10)},-1)
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{2Y1.0e1]}{\Y}{}
\pgfplotsassertequalstok{2Y1.0e0]}{\Z}{}


\CS normalized axis cs=(0,1)
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{1Y1.0e0]}{\Y}{}
\pgfplotsassertequalstok{}{\Z}{}


\CS normalized axis cs=(0,{min(0,-1)})
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{2Y1.0e0]}{\Y}{}
\pgfplotsassertequalstok{}{\Z}{}

\CS normalized axis cs=(0,1,-1)
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{1Y1.0e0]}{\Y}{}
\pgfplotsassertequalstok{2Y1.0e0]}{\Z}{}

\CS normalized axis cs=(0,{min(0,-10)},-1)
\pgfplotsassertequalstok{0Y0.0e0]}{\X}{}
\pgfplotsassertequalstok{2Y1.0e1]}{\Y}{}
\pgfplotsassertequalstok{2Y1.0e0]}{\Z}{}


% rel axis cs : only check the arguments of \pgfplotsqpointxy and
% \pgfplotsqpointxyz...
\def\pgfplotspointxaxis{}
\def\pgfplotspointyaxis{}
\def\pgfplotspointzaxis{}
\def\pgfplotspointminminmin{}

\CS rel axis cs=(0,1)
\pgfplotsassertequalstok{0}{\X}{}
\pgfplotsassertequalstok{1}{\Y}{}
\pgfplotsassertequalstok{}{\Z}{}


\CS rel axis cs=(0,1,-1)
\pgfplotsassertequalstok{0}{\X}{}
\pgfplotsassertequalstok{1}{\Y}{}
\pgfplotsassertequalstok{-1.0}{\Z}{}

\CS rel axis cs=(0,{min(0,-1)})
\pgfplotsassertequalstok{0}{\X}{}
\pgfplotsassertequalstok{-1.0}{\Y}{}
\pgfplotsassertequalstok{}{\Z}{}

\CS rel axis cs=(0,{min(0,-10)},-1)
\pgfplotsassertequalstok{0}{\X}{}
\pgfplotsassertequalstok{-10.0}{\Y}{}
\pgfplotsassertequalstok{-1.0}{\Z}{}
\end{document}
